This invention relates to a 5- or 6-alkoxycarbonyl-2,3-dicyanonaphthalene which is useful as an intermediate for synthesis of a tetrakis(alkoxycarbonyl) metal naphthalocyanine, and a process for production thereof.
In recent years, various attempts have been made to use diode laser as a light source, for example, in laser beam printers using an electrophotographic plate and laser beam as a light source. In this case, the wavelength of said light source is about 800 nm, and therefore there is eagerly desired an electrophotographic plate having an organic charge generating material which absorbs near infrared rays near 800 nm.
As organic dyes which absorb near infrared rays cyanine dyes have heretofore been well known, and metal complexes of oximes and thiols and aminated guinone derivatives and also known as dyes which absorb near infrared rays [Yuki Gosei Kagaku Kyokai Shi, vol. 43, p.334 (1985), Shikizai Kyokai Shi, vol. 53, p.197 (1980), and Shikizai Kyokai Shi, vol. 58, p.220 (1985)].
However, the cyanine dyes have a very low stability against light and hence their employement has many restrictions. The metal complexes of oximes and thiols are disadvantageous in that the metals are released from the complexes in a certain medium, resulting in loss of the ability to absorb near infrared rays. The aminated quinone derivatives are very poor in ability to absorb near infrared rays.
On the other hand, as sensitive plates which have a high stability against light and are sensitive in the vicinity of 800 nm, there have been reported those endowed with long-wavelength sensitivity by forming as charge generating material layer a thin film of metallophthalocyanine having a metal in group III or IV of the periodic table as central metal by vacuum evaporation, then immersing the thin film in a shifting agent solution or bringing the same into contact with vapor of the solution, and thereby shifting the inherent absorption band near 700 nm to about 800 nm (Japanese Patent Application Kokai (Laid-Open) Nos. 61-45249 and 60-260054). However, in this case, the metal phthalocyanine thin film having a metal in group III or IV in the periodic table as central metal which is used as a charge generating material layer involves the following serious problem. The thin film has essentially no absorption in the vicinity of 800 nm, and unless treated with a shifting agent, a sensitive plate formed by use of the thin film has no or low sensitivity to light near 800 nm (see Japanese Patent Application Kokai (Laid-Open) No. 58-158649).